Friday, January 14, 2011

Part of my most recent defense of the argument from reason, in response to the "God of the Gaps" charge.

So, I would maintain that there are gaps and there are gaps. It is not just pointing to an unsolved engineering problem in nature. First of all, the categories of the mental and the physical are logically incompatible categories. You start attributing mental properties to physics and you might end up being told that you are no longer describing the physical at all. Purpose, normativity, intentionality, or aboutness, all these things are not supposed to be brought in to the physical descriptions of things, at least at the most basic level of analysis. ¶ Let us consider the gap between the propositional content of thought and the physical description of the brain. My claim is that no matter in how much detail you describe the physical state of the brain (and the environment), the propositional content of thought will invariably be undetermined. ... As I see it, it is not a matter of getting a physical description that will work. In my view, the logicoconceptual gap is always going to be there regardless of how extensively you describe the physical. As I said earlier, bridging the chasm is not going to simply be a matter of exploring the territory on one side of the chasm. ... [T]he "God of the gaps" or even a "soul of the gaps" response to the argument from reason does not work. I am not saying that we just cannot figure out right now why the mental states involved in rational inference are really physical, I am suggesting on principled grounds that a careful reflection on the nature of mind and matter will invariably reveal that there is a logical gap between them that in principle cannot be bridged without fudging categories.

I am not sure what our ability to decode mind-talk from the brain would amount to. It would seem to me that certain brain-facts, (combined with facts about the rest of the physical world), would have to logically (!) entail some truths about our mental states. But physical statements cannot logically entail mental-state statements, any more than they can logically entail moral truths. So even if scientists could find correlations, the correlations would not be logically necessary.

But physical statements cannot logically entail mental-state statements, any more than they can logically entail moral truths. So even if scientists could find correlations, the correlations would not be logically necessary.

Under naturalism, in a deterministic universe, the ultimate laws of physics are axioms of the system, and the consequences of those laws are logically necessary. It all seems quite verifiable. If mental states are physical states, then they are logically determined by the physics.

In contrast, material facts don't determine moral facts because morality is fundamentally indeterminate. No matter what the outcome of an act, it is impossible to tell from the material results whether the act was good or not.

But the problem is that the mental states aren't deducible from the physical states. Stack the physical state descriptions up to the ceiling, and there propositional states will not be entailed. The physical underdetermines the mental, so if the mental is determinate (a presupposition of science) then the determination of the mental must come from some source other than the physical.

What would your response be to a naturalist who insisted that "purpose, normativity, intentionality or aboutness" really were parts of the physical description of things? Would it be that that just isn't naturalism anymore?

"If mental states are physical states, then they are logically determined by the physics."

I don't think that follows. Even if one accepts physicalism, one can still differ in the kind of necessity between different physical states. The mental could supervene by logical necessity (which I think is obviously false given the zombie thought experiment), by metaphysical necessity or merely by nomolgical necessity.

anon: What would your response be to a naturalist who insisted that "purpose, normativity, intentionality or aboutness" really were parts of the physical description of things? Would it be that that just isn't naturalism anymore?

Well, then I would have to ask what qualifies the objects as being physical. I mean you could convert the most blazing Cartesian dualism into materialism by saying that the Cartesian soul is just a funny kind of matter. But if you do that, you then raise the possibility that God is a material being, in which case you have all but emptied the concept of the physical of any meaning.

I would say to the materialist: You are the materialist. Just as it's my place to tell you what beings I believe in, it is your place to tell me what you mean by matter. We assume that your position excludes mine, but without a concept of "the material" that need not be the case.

"Can we think propositions without language? What role does our inner monologue play?"

I hope this doesnt derail this thread too much. I always thought it's obvious that there are able to think propositions without language. When I was taught the late Wittgenstein I was really surprised to see that many think otherwise.I am cursed with a bad memory, so I'm often in situations where I want to talk about a person, a country or a movie but can't recall the name. I certainly have the meaning, I just don't have the words for it.

I always thought it's obvious that there are able to think propositions without language.

Well, I'm not sure it's obvious, but I actually agree with you.

However, in agreeing with you, I don't think I change the overall thrust of my complaint.

When you think "What was the name of THAT movie", you're probably pointing with language (the "THAT") to what you see in your mind's eye or in the fragments of your memory that you do retain. If we find that we can identify the mind's ear, we ought just as easily be able to look at the mind's eye at the same time. Either way, the train of thought will be clearly decipherable.

But the problem is that the mental states aren't deducible from the physical states. Stack the physical state descriptions up to the ceiling, and there propositional states will not be entailed.

I just can't see any good argument for that at all. If we can hear what the mind is saying, as cashed-out in terms of the words the mind uses in conversation, what's under-determined about that?

I'll assume you're referring to an intentionality argument in the above. I expect you might make an analogy to a computer. The body is a machine that results in propositions being sounded out internally, which we then decode. Your concern would be in regard to what these propositions refer to.

I've given the following argument many times, but no harm in giving it again. :P

The neocortex learns to recognize patterns in its environment (and patterns in itself) by forming structures/circuits that switch on in the presence of those patterns. A word refers to anything that would turn on that circuit. Intentionality is there because a word refers to something fairly specific, e.g., "apple" refers to anything that switches-on the recognizing circuit that was trained on apples.

IOW, the mind's words refer to patterns found in the mind's past. I'm not seeing a problem.

This is along the lines of suggesting that we're decoding thought and inner monologue when we decode music from an mp3. In fact, along the lines nothing. It's exactly the same thing. Music on an mp3 is decipherable by a mind. What would be read off a brain from sound or image would be decipherable by a mind.

But to play a sound is not to decipher it, anymore than a CD player understands music or lyrics just because it plays it.

Doctor Logic: But surely there can be plenty of stimulus and response without appreciation of meaning. "Recognizing pattern X" has to be reduced to some kind of behaviorist analysis before this kind of reduction has any hope of working. Is there a difference between "X behaves as if it recognizes pattern X" and "X actually recognizes pattern X."

Vic: "I am suggesting on principled grounds that a careful reflection on the nature of mind and matter will invariably reveal that there is a logical gap between them that in principle cannot be bridged without fudging categories."

I find it amusing that Tim McGrew thinks you "nailed it" here.

You're arguing that we cannot get to a mind from the fact that there is only a brain.

So, let's talk about the mind. If there is a mind can we get to a brain? Think about this. You have merely reversed the argumentation but it leads to the same conclusion. I maintain that there is no logical connection between the mind and the brain. If we presume there is a mind then how does it tell the brain what signals to send to the arm such that it moves? Logically, unless there is a point of contact between them, the mind cannot interact with the brain. You know the problem.

What's your solution?

Let's say you have none, or at least, let's say I'm not persuaded. Then we are at a logical impasse.

What to do then?

Trust the sciences. Science repeatedly disconfirms that there is a mind. Drugs, strokes, electromagnetic probing, and a nail through the brain can and does change a person's emotions, ideas, thinking patterns, and a man's personality itself.

In fact, as neurologist Sam Harris has said, if there is a mind there is no reason for God to have created us with brains. If the mind tells the brain what signals to send to the arm then it can by-pass the brain altogether and simply send signals to the arm.

Not every conceptual argument for the distinctness of two things is an abuse of Leibniz's Law. Consider how you would argue (if you would, which I hope you would) that the number 5 is not identical to your toothbrush.

John,

If you don't know what the phrase "logical connection" means, then it would be wiser not to try to do philosophy. You clearly have no idea what the discussion is even about.

Can you explain how your argument is any different from the old arguments for Élan vital? It was said "but life is just a separate category from non-life; there must be some immaterial essence infusing life that makes it alive."

But now we know that life is just complicated chemistry. The Élan vital arguments were just arguments from ignorance.

Not only did the claims of a "life force" turn out to be false, but these claims never had any explanatory power in the first place.

Here is a simple substitution:

"First of all, the categories of life and chemistry are logically incompatible categories. You start attributing living properties to chemistry and you might end up being told that you are no longer describing the life at all."

But now our best descriptions of life are detailed description of organic chemistry. Life just is an intricate dance of organic molecules.

Our understanding of the mental grows daily from studying the brain. It seems to me your argument is doomed for the dust bin of history. A dust bin overflowing with discredited useless concepts like Élan vital, phlogiston, luminiferous aether, hylomorphism, and so on.

Tim: I was just being lazy on my text messager instead of writing out: the problem is moving from the apparent conceptual gap that presently exists between brain-facts and mind-facts to a substantive metaphysical difference. Just bringing attention to an apparent conceptual or "logical" difference is not enough.

As for toothbrush and number 5, we'd still have to be careful of going from differences in our concepts to differences in the things. That's just not sufficient to establish breakdown of identity. We'd have to establish, in cases where it is legitimate, that it is legitimate (for instance what if it were the number 5 and the set of all sets of things with five members?).

I'm all for putting things into wider context. But confusing "logical connection" with "causal connection" was not a promising beginning.

The "how can" challenge to mind-body interaction is a complete red herring: Pratt articulated the obvious and crushing response nearly a century ago. It astonishes me that it still lives on. I guess religion isn't the only place we find memes, eh?

Sure: care is needed. But some conceptual distinctions are stark. Asking about the relation between 5 and a set of sets is asking about the relation of two non-physical things; the relation between 5 and your toothbrush is a relation between a non-physical thing and a physical thing. There, we really are in a position to push an inference.

Any minute now we're going to plunge into the modal argument and the question of the relation between conceivability and possibility ... :)

[A]s neurologist Sam Harris has said, if there is a mind there is no reason for God to have created us with brains. If the mind tells the brain what signals to send to the arm then it can by-pass the brain altogether and simply send signals to the arm.

No matter who said it, this is an awful argument.

The dualist would just respond that they know full well that the brain is important for processing sensory inputs, motor control, interaction with the endocrine system, etc.. It is a complete nonsequitor that their position would imply that "god didnt' need to create us with brains."

First let's set aside the fact that it assumes all dualists think that God has any hand in it, which is false. The majority of dualists I know are atheists.

But assuming that assumption isn't bogus, you might as well argue that dualism implies we don't even need muscles, as God could have made it so the mind could skip the muscles and makes its connection directly to the skeleton like a marionette.

So, why aren't we marionettes in that sense? Seems obvious: muscle works really well to move things, but are not good at processing complex information. Kidneys work really well to filter out waste products. The brain, the organ intimately involved with thinking (under every view) is a wonderful processor of complex sensory information, able to receive signals, integrate information, and transmit commands like no other organ. It actually seems ideally suited to interact with a mind that needs to deal with large amounts of complex information and influence decisions.

Maybe that's why God created the brain to interact with the mind: because it's ideally suited to do so, unlike muscles or bone or the heart. Not much of a stretch of the imagination. That's what the evidence shows, so why wouldn't a dualist believe it?

There are other good arguments against dualism, but the claim that dualism implies we don't need brains? Worst I have ever seen.

Incidentally, while I think there is no single definitive knock-out punch against dualism, a better related argument would be: given all the neuroscience we know, it isn't clear what is left over for a nonphysical mind to do within the brain. What is the causal role of the mind within individual neurons, and what is the evidence that it plays this role?

Tim: starkness isn't very well defined. In contentious cases like minds and brains, to just assert the relevant difference is there would be question begging. The problem is, the actual arguments are not very strong.

BDK I just don't see what you're saying. Maybe you know more than I on the subject. I do agree that "it isn't clear what is left over for a nonphysical mind to do within the brain. What is the causal role of the mind within individual neurons, and what is the evidence that it plays this role?"

I think you assume some things that Harris doesn't need to. Maybe we don't need muscles either if there is a mind. But so what? The point is that unless you can tell me why we need a brain then it doesn't matter if we God created one. I think you're assuming some things that his argument doesn't need to assume.

John it's just a weak argument. There are better ones. They can just say the brain is needed to take in information from the world (after all they realize that when you lose your eyes you become blind, they would just say that this is because the inputs from the brain to the mind are cut off). They can say it is needed to control muscles after the mind has decided what movement to make (after all, sever your spinal cord, and you can't move). (Not to mention it is needed to interact with the endocrine system, circulatory system, etc...not just overt behavior).

It's too easy for them to respond. Harris was likely making an offhand quip that he hadn't thought through. If I had his email I'd ask him.

I guess you could say that strictly the brain isn't logically necessary, but then nothing is in some sense. We could get into weird theological disputes like why is the planet Mercury there, it isn't necessary that it be there it might not have existed at all. Any real, versus straw, dualist, will go with mind-brain interaction because that's what the evidence supports (Lashley, Popper, Eccles, Descartes, etc were the opposite of dummies).

I look at it not as a stone in a good overall case, but as an acid that weakens the overall case against dualism. AS you might ask Victor, try getting that claim published in Nature.

My positive view I am writing up right now. It will be ready in a couple of months. I have written extensively on the topic at my neuroscience blog with table of contents here.

What I am presently writing is a response to the types of conceptual arguments that Victor presents, it's going to be a long one about 50 pages it has been about 16 years in the making, festering since I heard Chalmers speak in Tuscon in 1994.

I guess you could say that strictly the brain isn't logically necessary...

Cool! Now we're talking. You understand.

but then nothing is in some sense.

Not true at all upon the supposition that there is a creator god who cares to have free willed creatures who love him. Care to elaborate?

I maintain that on the supposition of a creator god that the vastness and age of the universe isn't necessary. He could have created a world on a flat disk for this. The question at that point is why did god create unnecessary things? The burden of proof is on the theist to show why unnecessary things were created.

Any real, versus straw, dualist, will go with mind-brain interaction because that's what the evidence supports (Lashley, Popper, Eccles, Descartes, etc were the opposite of dummies).

Nope. Theists must at least deal with the evidence so that's what they are forced to do. The evidence is that our brains do the requisite work. This is obvious. The question for theists is how to smuggle in the mind. Harris, like me, maintains that if they want to smuggle in the mind then there is no need for the brain.

AS you might ask Victor, try getting that claim published in Nature.

Nature is a scientific journal. This is a philosophical argument that grants the theistic assumption that there is a mind. It wouldn't be accepted in Nature for that reason.

Look Bob, you do not take your theology very seriously at all. If there is a mind then it can sense the empirical world on your own assumptions. If there is a mind we do not need our senses. Get it? If there is a mind that can interact with the brain then it can control the brain. If it can control the brain then it knows what the brain is doing. How it does this is left unexplained, but if we take that position seriously it can. Now if it can sense the brain then it can sense the outside world and so we do not need the five senses.

You people need to be more consistent here. Consistency, that's all I ever ask.

But let's assume God created us with senses anyway. The mind supposedly has the characteristics of memory storage, critical thinking, decision-making and so on. What need then of a brain? I simply don't see it based on theistic grounds.

There is no logical problem involved in saying that non-physical things and physical things can interact causally. The fact that the categories of mental and physical are mutually exclusive doesn't go anywhere toward showing that items in one category cannot interact causally with items in the other.

John, but that just repeats what Tim said: the *categories* are mutually exclusive. How does that show that causal interaction between the two categories is impossible? Take everything that is a dog, and place it one one category, and everything that not a dog, and place it in another. Does it follow that because the mail-carrier is in the latter category that the dog can't interact with him? I'll bet the mail-carrier wished it were that easy! (I can picture a mail-carrier running away from a Rottweiler while cursing the Venn diagram his boss comforted him with!)

"both the mail carrier and the dog are in the class of objects that are material.The logical problem arises between material and non-material objects that doesn't arise between objects that are material."

Right, but I took your argument that there is a logical problem to be that since we can place X and Y in logically distinct categories, X and Y cannot causally interact. That seems to me to be the only way to understand the following (which was said in response to Tim's request, "If you think there is a logical problem, please do share it"):

"There is the category of material which I'll call X.Then there is the category non-material, which is the anti-thesis of X which I'll call nX or not X.Use Venn Diagrams to see the result."

As far as I can see, your argument is that because X and not-X can be places in logically distinct categories, they cannot causally interact. But I can place dogs and mail carriers in logically distinct categories, too. I suppose I don't understand the argument. (I do understand the 'interaction problem' -- though on some types of dualism, there is no such problem -- but I don't understand your argument that the problem, which I take to be causal, is logical.)

A mind by my definition cannot act on material object unless it participates in something material for that interaction to take place. But since the mind by definition does not include any material properties it cannot act on a material object by definition.

Thus is the logical problem.

So the question becomes whether or not by your definition the mind contains material properties.

When one supposes (a priori) that the non-physical part of mind performs functions that the physical part doesn't, then there are many functions the brain performs that could have been performed by the non-physical part of mind. This is what John/Harris meant when they said that non-physical parts of minds could talk directly to muscles, etc.

But when you can't clearly say what the non-physical part of mind is doing, and it's only doing what which the physical part can't yet explain (almost nothing), then you have a God-of-the-gaps argument.

In Bayesian terms, it's daft. Conceptually, for every function X that the mind performs, it might have been performed by the physical part or by the non-physical part (e.g., X could be, say, the ability to recognize a friend and elicit feelings of fondness for that person). We can imagine a world in which that linkage was non-physical, and that it was impossible to cut into the brain and disrupt that function and only that function. As we know, nothing like this has ever been found. In effect, dualists suppose that we're seeing that VERY special kind of dualism that looks in every way (so far) exactly like physicalism.

Dualists seem blissfully ignorant of this.

Here's an analogy. Physicalism is the prime suspect. The fingerprints are found at the scene, and on the murder weapon. Witnesses place physicalism at the scene. Physicalism had means, motive and opportunity. But the dualists say that physicalism was framed. Their evidence? They don't know what mode of transportation the suspect used to get to the crime scene. That's a gaps argument.

Dualists would say that it was impossible for the suspect to reach the crime scene. But what is their argument for this?

They claim that what we experience as intentionality is not implementable in physics. But they have not rigorously defined what intentionality is! They don't really know what it means relative to our own thinking, so they can't say what it would be relative to a brain. Intentionality is treated as something ineffable and mysterious. Well, unless a rigorous definition is forthcoming, they really don't have a good argument for saying physics isn't responsible.

The question is, if one of my thoughts lacked intentionality, how would I know? What does a non-intentional thought look like?

I've proposed an answer to this before, but I want to hear from dualists.

Not only would it never get published in a science journal, no philosophy journal would touch it because it's just a bad argument.

Why not argue that the retina isn't necessary if dualism is true, because the mind could directly sense everything going on in the electromagnetic environment? Would you endorse that argument? You should, because it's the exact same argument.

And it is just as silly, mainly because no dualist has ever claimed that the retina is logically necessary. They don't know why we have a retina, but we do, and it's really good at what it does. THey never would agree to the premise of the argument that they believe that every single thing the brain does must be necessary, and could not in principle be done by an immaterial mind.

The argument is a refutation of a view that nobody has ever held, a transparent straw man.

Real dualists, like Popper, Eccles, Lashley, struggle to work with the biology, not against it. Sure, maybe God could have built us without eyes so our minds directly interacted with photons in the world. But obviously that is not how we are built. Their claim is that the evidence supports mind-brain interations in the central nervous system (e.g., for Eccles in synapses).

Not to mention most dualists are not theists, so this whole argument is moot as an attack on dualism more generally.

And I gave reasons why building us with a brain might be a good design of mind-brain interaction, rather than mind-femur interaction.

I can't believe I am having this argument, it is so obviously weak I hope others will take up the slack I don't have the patience.

Regarding why dualists would think we need a brain, C. S. Lewis has an interesting argument that addresses this question, or something close to it, in THE PROBLEM OF PAIN. The discussion is about how self-consciousness and free will would be impossible if we didn't have any bodies and if there were no material nature.

Now, if you're asking, "if dualism is true, then why do brains exist -- not nature, or our bodies; just brains --? Well, I suppose one explanation could be that having brains allows us to make certain kinds of changes to our minds that we couldn't make if we didn't have brains. It alos allows for a kind of third-personal perspective on parts of our minds, or things intimiately related to mind-functioning, that we couldn't have if we didn't have brains. These might be important things.

Of course, substance dualism isn't the only kind of non-materialist view about the mind. One could also take up a thomist position.

Note also I agree with John that the interaction problem is nontrivial. I'm more interested in blocking arguments against naturalism than providing positive arguments against dualism: my take is that the best argument against dualism is the methodical construction of an alternate theory, and this is already underway, while dualism hasn't changed all that much in 400 years.

If Feser, or anyone, could give a succinct and intelligible description of hylemorphic dualism, I would be grateful. I tried a few weeks ago to pull one out of some folks to no avail, other than a link to a tangentially related paper on personal identity over time.

John is pushing the following still at his website:The brain ends up being unnecessary on the hypothesis there is a God who created the mind. Or you could perhaps give me one function of the brain that could not be performed by the mind if there was one.

Just one.

John let's formulate your argument...

Consider some function X that the brain in fact carries out (e.g., phototrandsuction).1. It is logically possible that an (immaterial) mind could do X.2. If it is logically possible for a mind to do X, then the brain is not logically necessary to do X.3. Therefore the brain is not logically necessary for X.

Do this for every value of X, and we see the brain is not logically necessary for anything.

Does everyone see the problem with this argument? I have McGrew-baked cookies available....

Tim, I see. Definitional appologetics are clearly at work in your definition of the mind.

Soooo, let's show you how to play that language game since two can play it. Remember Vic said:

"I am suggesting on principled grounds that a careful reflection on the nature of mind and matter will invariably reveal that there is a logical gap between them that in principle cannot be bridged without fudging categories."

So, is it a logical gap as Vic claims or a causal one?

Let's define a brain as a physical entity capable of consciousness that goes beyond the physical matter of the brain.

There. That wasn't so hard, was it? Vic therefore has been shown wrong. It is no longer a logical gap but a causal one by definition.

Your definition of a brain strikes me as bizarre. Depending on how you define the brain, I have not trouble with the idea that the mind is the brain. But the brain, or parts of it, have to have characteristics that are atypical of ordinary matter, otherwise thinking would not be possible. It would have to have intentionality as a property at the most fundamental level, purpose at the basic level, subjectivity at the basic level, and normativity at the basic level. Good luck getting that by the skyhook police.

Seriously: you began by trying to argue that there is a logical problem for Cartesian dualism. If there is, then it must be a problem that cannot be evaded even on the Cartesian's own terms. But in this respect, the "how can" objection fails.

I readily grant that there is a metaphysical mystery about the nature of causation. But it is a mystery for everyone, not just for the dualist. It isn't cricket to try to saddle the dualist with it as though it were a special problem for him.

BDK, I do not think it is logically possible for an (immaterial) mind to do X. And I do not think it is causally connected with the brain should it exist.

But if we grant the theist view that it is not only logically possible for an (immaterial) mind to do X but that an (immaterial) mind does indeed have a causal connection to the brain, then even though I disagree with the theistic view about what an (immaterial) mind can do I argue that upon their own suppositions there is no necessity for the brain.

Actually, I cannot even conceive of an argument against this scenario if we grant the theist's views. That's the point where Doctor Logic agreed with me who then went on to make his own point, returning this thread to the original point of Vic's post.

Then it's on to my point that when we both have difficulties explaining some phenomena then we should look a demonstration instead coming from the sciences. Anything can be explained. What we need is a demonstration. You know like strokes drugs crowbars and their effect on the so-called mind. There really should be no reason why I can change how your mind thinks by damaging your brain upon theistic suppositions. The mind then is an unnecessary hypothesis.

No traction, because the interactive dualist positively expects the mind to be affected by damage to or drugging of the brain. You can't argue against view X by pointing out that the things X predicts do, in fact, come to pass.

Chisholm drew some amusing pictures representing the major views on the relation of mind and body -- interactionism, epiphenominalism, psychophysical parallelism, etc. It was reproduced in one of the little Prentice Hall textbooks; very funny, but also very helpful as a way of teaching the basic views.

Do you have in mind some interactive dualist who was forced into that position from being a non-interactive dualist? Because no names are coming to mind. And if that's not a major path, then you're creating, and then knocking down, a straw man.

John I know you don't agree with premise 1, but it is part of your reductio right?

Premise 1: 1. It is logically possible that an (immaterial) mind could do X.

This is the claim that ends up with the reductio, that the brain isn't logically necessary to do X, right? That's the whole point.

If you aren't using 1, then why would you keep saying that there are all these things the mind can do under dualism so the brain isn't necessary? That's what 1 is expressing: that function X can be carried out by the mind.

I think maybe one oddity that John is pointing at is that on Cartesian dualism, mind and body are so ... well, they're so *separate*. I don't know if there's anything to this worry, or even if it's rigorously expressible. For whatever reason, though, Hasker's emergent dualism seems to me to eliminate this worry: if the mind is an immaterial substance that emerges from a certain configuration of a certain kind of matter, and can influence that matter after it emerges, then I feel like we have more of a story about why there are immaterial minds to begin with.

But emergent dualism is, at the end of the day, just a species of substance dualism; it might even just be Cartesian dualism with a few things that were left implicit being made explicit.

(However, I don't think it is just Cartesian dualism; I think emergent substance dualism does not allow for the possibility of minds naturally surviving the destruction of their brains, whereas Cartesian dualism might suggest, for reasons of the sort Plato gave in the Phaedo, that the mind is naturally immortal.)

One major problem with the argument is that it attributes too much to the dualist, thereby making a straw man. The dualist doesn't need to say that just because function X could possibly done by a mind, that in fact it is carried out by a nonphysical mind. Sure, a nonphysically mind could (logically, anyway) interact directly with photons. That doesn't make the dualist committed to that reality, in actual fact.

That's only one sense in which John's argument is completely getting confused about types of necessity and possibility: perhaps Tim could take him to modal logic school.

That was only the most obvious problem. Others I already pointed out. The consequence of this confusion is that he ends up attacking a version of dualism that nobody in reality has ever held, and never will hold. That is, a version of dualism in which logical possibility implies actuality.

(The problem should be obvious if you substitute 'heart' for 'immaterial mind'...think Aristotle).

Frankly, I am so surprised that John has pushed this argument four times now, an argument that it is so clearly confused and wrong, as has been pointed out to him, that I realize just how self-referential are his claims about extreme cognitive bias and inability to be rational.

I agree John, that you should follow the science, and stop trying to do philosophy.

My hunch is that Harris, if he ever actually made that argument, reversed the terms. He meant to say that brain knowledge makes immaterial minds unecessary. Not that immaterial minds make brains (in every single respect) unecessary.

Sure, they make brains unecessary for X, where X is what the dualist thinks the immaterial mind is for. But that's it. This weird extension to brains as a whole? Total nonsequitor.

Let me say it again. If someone takes seriously the notion that there is an immaterial mind that thinks, stores information, responds to the stimuli of the senses, and causes the brain to send signals to the body (that is, that it can somehow sense the material world without any sense data at all) then there is no reason why human beings need brains.

There can be no counter-argument to this. All counter-arguments to it do not take seriously that there exists an immaterial mind that thinks, stores information, responds to the stimuli of the senses, and causes the brain to send signals to the body (that is, that it can somehow sense the material world without any sense data at all).

John:You are saying that if the dualist thinks the immaterial mind does everything brains do, then brains aren't necessary.

I get it.

The problem is that no dualist has ever satisfied the antecentent of that conditional. It is a refutation of straw dualism, not any real dualism that has ever been advocated.

Start with Descartes, and go from there. See if the argument works.

Descartes was extremely modern in his understanding of animal behavior, and thought all nonhuman behavior (and most processes in humans) could be handled mechanistically (the vitalists despised Descartes, ironically). He realized that brains were extremely important in these processes.

Now you could modify it so it is not a straw man. E.g., they think the immaterial mind is sufficient for all conscious experience, so brains are not necessary for consciousness. That would not be a straw man, but an instance of actual arguments from dualists (or at least Descartes). Then you could say why we think the brain is sufficient for consciousness etc. etc..

That would be the way to argue. Pick something a dualist has actually said they think we don't need brains for, and argue that we do need brains for them.

When you try to say they believe the mind does everything the brains do, so brains become totally unecessary, then it becomes a howler of straw.

Again, start with Descartes.

Inexplicably, you add:What force such an argument has is an entirely different issue.

No, it's precisely the issue because you used the argument as a refutation of dualism. If the argument has zero force against any real opponent, but here, in an article on the web, and an entry at your blog you are touting it as an objection to something real, then you have a serious problem.

Not sure what you think you are getting from this constant appeal to Harris' putative authority on what is a flimsy philosophical argument, when reason so clearly shows the argument is bogus. Careful of this tendency to genuflect to scientists over reason.

Just let it go John. It doesn't work. There are much better arguments against dualism. I wish this one worked, frankly. I showed how you could tidy it up into something more interesting. Maybe take that route, but as it stands it fails.

Before writing about dualism, perhaps read Chalmers' book 'The Conscious Mind.' That would at least help you see the territory more clearly, give you something a real dualist has said.

Surely, the argument is like this. If physicalism is true, then every aspect of mind must be the results of the brain (or brain + body). So, if physicalism is true, then when we study any brain function, the probability of finding that function to be caused by a physical mechanism is 1. It's like tossing a two-headed coin and getting heads.

But if dualism is true, not all functions of mind are physical. There will be some functions that are non-physical, that are obviously performed, but which we cannot disrupt using physical means. Under dualism, the probability of finding a mechanism to be physical is P, say, 50/50, like flipping a coin and getting heads or tails.

Even if our prior probability for physicalism was initially tiny, it would still be irrational, a posteriori, to believe that dualism is true.

Do a Bayesian analysis. I just put together a little spreadsheet. If you start from uniform priors, and assume a 50% chance that any mental function would be physical under dualism, then after just finding 20 functions implemented physically, confidence in dualism will fall to 0.0002%.

The dualist will typically answer that he doesn't believe in the sorts of dualisms that are ruled out by these experiments. Good. But dualists have forgotten the experiments were even done. You don't get to walk in late in the game and pretend your priors are uniform. Dualists are fine-tuning their dualism to be that special kind of dualism that looks exactly like physicalism. And I think this is what John is referring to.

BDK, I took a master's level class with Bill Craig on Descartes, and I have taught Cartesian thought for Introductory to Philosophy classes. Therefore, you probably do not understand him as well as I do.

This argument merely concludes the brain isn't necessary if dualists take seriously that there is an immaterial mind.

The argument is that dualists do not take seriously what dualism actually commits themselves to. They are not being consistent.

They are reasoning a posteriori based on the evidence that they must take into consideration about what the brain does. They cannot hold to a dualism that does not admit this evidence.

Fine.

But I'm arguing apriori. That prior to examining the evidence for the working of the brain that there is no reason why a dualist should think we need minds.

There can be no argument against this if you understand the argument properly.

So in the last two posts, we have Loftus saying that his argument wasn't meant to refute dualism, and then saying why it refutes dualism. Make up your mind.

Because they are using data about brains to constrain their reasoning about the sphere of the mental, that somehow makes them suspect? If their reasoning isn't completely a priori, and they sneak in actual data, that falsifies their entire project? It doesn't follow.

Let it go, you are being stubborn. Read Chalmers, get up to speed on what actual dualists think, and get back to us. Get clear on your argument, what you are refuting, what you are not refuting, what Harris actually said, and get back to us once you have thought it through dispassionately.

Let's see Tim, it was you who told me that you are impressed with the reasoning skills of BDK.

No, John, I see no reason to revise my judgment. I'll just add that since the intersection of neurophysiology and consciousness is BDK's field of specialization, and since he has advanced degrees in both fields, it's pretty bold of you to assume that your having had one graduate class on Descartes and taught undergrads places you in a superior position to understand what is going on here.

But degrees are only markers for competence anyway. Once one has displayed competence (or incompetence), the degree matters very little.

Really? Then would you please address the Harris/Loftus argument. First, do YOU understand it? Second, do tell us why the brain is an a priori necessity if there is an immaterial mind having all the characteristics that by definition it must have the characteristics it has.

You never addressed that. If you see no reason to revise your judgment on BDK than I would expect some kind of a defense than an assertion about his credentials.

Then would you please address the Harris/Loftus argument. First, do YOU understand it?

As well as one can understand any poor argument: I see the claims, but they look like a modal train wreck.

Second, do tell us why the brain is an a priori necessity if there is an immaterial mind having all the characteristics that by definition it must have the characteristics it has.

I don't think it's necessarya priori. This is not a claim that any dualist I know wants to endorse. Why on earth would you (or Harris) think it is essential to dualism to make such a strong claim? It sounds like you are trying to claim that "it is the case that p" entails "it is necessary that p." But that is a modal howler.

John, let's turn it around: you can't show, under materialism, that the brain is logically necessary for anything. Therefore, materialism is false.

Before you answer in a quick way, without thinking, make sure you understand the difference between nomic and logical necessity. Also, keep in mind how many Greeks believed the brain was for cooling blood.

John while I've been agressive here, I'm not kidding when I say, please read David Chalmers' book (The Conscious Mind) to get clear on different types of necessity, what a real (property) dualist argues, and how such dualists undeniably take neuroscience and pscyhology into account in their arguments.

It is fair to say that anyone that hasn't grappled with Chalmers, and is a materialist, hasn't grappled with consciousness as a metaphysical problem.

I want you to present good arguments against dualism, I truly do. I suggested how you might salvage this one, but as is you really should just stop in the name of credibility.

John, to get started, read the first four papers in the first section here. Consider it part of an outsider test for materialistic theories of consciousness. His book is better, more comprehensive, but as a start those are some great free resources.

And what about people with separated cerebral hemispheres, and the ways their hands and half-brains respond to different questions simultaneously? (And the way the speaking half of the brain fabricates excuses for why its other hand responded as it did, without knowing the actual question that that other side of the brain was busy answering.)

I liked the video I saw of one hand being unable to assemble a simple puzzle on the table, while the other hand did it with ease. Then when the split-brain patient was asked to use both hands at the same time to solve the puzzle, the hand that could do the puzzle the non-speaking part of the brain had to keep pushing away the other hand, frustrated with its incompetancy. Check youtube for videos on split-brain experiments. The non-speaking part of the brain cannot verbalize but it understands speech and can also point to reply to questions. One patient had the speech part on the opposite cerebral hemisphere, and another patient's non-speaking side could respond with simple one word answers. But most times that hemisphere can only point to things in reply to question.

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About Me

I am the author of C. S. Lewis's Dangerous Idea: In Defense of the Argument from Reason, published by Inter-Varsity Press. I received a Ph.D in philosophy from the University of Illinois at Urbana-Champaign in 1989.